Heretofore, it has been generally been known to provide filtering apparatus in which the filter unit is arranged to be connected for normal filtering flow of the fluid to be filtered in one direction through the filter, and periodically reverse the direction of flow through the filter to remove the accumulated filtered out material. In many installations, the reverse flow or backwashing procedure, as previously practiced, is not entirely satisfactory for the reason that much of the filtered out material becomes lodged in the filter and is not effectively removed by the usual reversed flow or backwashing process.
In U.S. Pat. No. 4,055,500, I disclosed a unique filtering apparatus having a backwashing system capable of initiating a backwashing flow with an explosive-like initial surge of backwashing fluids. The explosive-like surge of the backwashing fluid is accomplished using a quick-opening valve, actuated by a linearly traveling valve stem disposed on the outlet side of the valve. Such filtering apparatus has been found to be considerably more efficient than filtering apparatus of the prior art due to the increased efficiency of the backwashing operation using the explosive-like initial surge of backwashing fluids.
Although the filtering system disclosed in U.S. Pat. No. 4,055,500 has been found to be considerably more efficient than filtering systems of the prior art, the filtering system disclosed in U.S. Pat. No. 4,055,500 is not as efficient as it might otherwise be. This is because that system requires backwashing fluids to exit the filtering system via an outlet line having at least one 90.degree.. This bend is necessary in the filtering system disclosed in U.S. Pat. No. 4,055,500 because of the construction of the quick-opening valve, actuated by a valve stem traveling linearly from the outlet side of the valve. Such 90.degree. bend has been found to significantly increase the pressure drop of the surging backwashing fluids, and consequently, significantly reduce the efficiency of the backwashing operation.
Accordingly, there is a need for a filtering apparatus of the type disclosed in U.S. Pat. No. 4,055,500 which does not require a 90.degree. bend in the backwashing outlet line.